Diazotype photographic printing paper



' Patented Oct. 1,1940

PATENT OFFICE nmzomn rnoroomrnio rnmrlno PAPER Maximilian Paul Schmidt and Oskar Siis, Wiesbaden-Biebrich, Germany, assignors to Kalle .&

Germany No Drawing.

Aktiengesellschai't,

Wiesbaden-Biebrich,

Application October 10, 1936, Se-

rial No. 105,088. In Germany October 12, 1935 The present invention relates to diaaotype photographic printing papers.

It is known to manufacture light sensitive diazotype photographic printing papers which contain in the layer the two dyestuff components,

namely the diazo compound and the azo component, serving for the production of the picture or the like. Papers of this kind only require for their development a ,treatmentwith alkalis, for m example ammonia or soda solution. It has also been proposed to apply the alkali serving for the development alone or in admixture with an azo component on papers sensitised with diazo compounds before the exposure, the said alkali and/or azo component being applied in powder form. Papers of this kind can be developed by a simple treatment with water or steam respectively. They possess, however, only very poor keeping qualities. Moreover, they have the disadvantage that when in use they easily become dusty, i. e. give oil fineparticles of the alkali and/or the 2.20 component, which gives rise t6 considerable inconvenience to the operator carrying out the work of printing.

35 One object of the present invention is the production of light sensitive materials to be developed by treatment with water which materials have better keeping qualities than the known materials of this kind. Another object of the invention is the production or light sensitive materials oi the mentioned type which do not tend to give off line particles or the substances which have been applied in powder form.

According to the invention, light sensitive diazotype materials are provided which contain as developing means a coupling component and a neutral salt of a weak base with a weak acid which latter is fugitive with steam, i. e. can be volatilized by means of steam below its normal boiling point. Such salts are the acetates and iormates of zinc, cadmium andlead.

It is supposed that during the development of the new diazotype layers with steam, oiiides or basic salts are formed from the said acetates or iormates respectively with the, elirnlnation of the hydrolytically separated acids whereby the diminution of the acidity of the layers necessary for the coupling process is obtained.

as diazo compounds advantageously such which couple rapidly, i. e. couple under neutral or acid conditions areused. 1

We have discovered that the said light sensitive materials in which either the said neutral salt or the coupling component or both have been applied to the support in powder. form, forexatmospheres.

ample by rubbing the powder in, can be obtained practically free from dust by treating them after the application of the constituents, with a strong current of air, for example by blowing the air on to them or by sucking it 012 from them. The 5 power of-the current of air may amount to some In place of air other inert gases may be employed. It is a surprising fact that during this treatment a suificient quantity of the developing substances and the azocomponents, 10 when they have been applied by rubbing them into the paper, remains behind to enable complete development still to be effected, whilst, on the other hand, inconvenience in the working operations is avoided. For further preventing a m slight development of dust when employing pas pers of the aforesaid kind they may, after the above described treatment, be further treated with rollers, whereby a better closure of the surface of the paper and consequently a better adso herence of the powdered substances is obtained.

The following examplesillustrate the invention:

1) Paper sensitized with a solution or 36 grams of the zinc chloride salt of the diazo comdb pound of 2' 6'dichlorbenzyl-d-amino-l-aniline and 30 grams of citric acid has rubbed into it a powder consisting of 125 grams or phloroglucine and 250 grams or calcium acetate. After the rubbing in operation loose powder remaining on 39 the surface of the paper is removed by blowing dry air under pressure on to the latter. By subsequent caleudering an increase of the power of adherence of the powder which still remains is obtained. Paper subsequently treated in this W way after the rubbing in orthe powder, in contradistinction to paper which has not been so treated no longer becomes dusty, l. e. yieldsup dust. The speed of development and the intensity are retained in their entirety.

(2) Paper is sensitized with a solution contain- -ing 9b grfams'oi the diazo compound of l-aznino l-benzoylarnino-2,5-diethoxybenaene, d5 grams of citric acid and 3 litres or water and has rubbed into it by mechanical means an intimately mixed powder consisting of 125 grams or phlorogluciue and 250 grams or also acetate. if desired, both in this case and in Exainple l, inert substances, such as starch, may be added for diluting the powder. The alter-treatment of the paper is carried out as described in Example 1. In place of the zinc acetate also the corresponding formic acidsalt may be employed.

(3) The sensitization of the paper is effected 5 as in Example 1. The powder applied by rubbing it in has the following composition:

- l Grams Phloroglucine 125 Lead acetate 318' Grams Phloroglucine 60 Cadmium acetate 200 Glaubers salt (sodium sulfate) 120 The after-treatment of the paper is carried out as in Example 1.

(5) Paper is sensitized with a solution containing 15 grams of the diazo compound of 1- phenylthioacetylamino lfi-dimethoxy 4 aminobenzene, 5 grams of citric acid, 5 grams of boric acid; 5 grams of aluminium sulphate and 1 litre of water and has rubbed into it a mixture of 60 grams of phloroglucine, 200 grams of cadmium acetate and 120 grams of Glauberslsalt. The

after-treatment is carried out as in Example We claim:

1. A light-sensitive material which comprises a diazo compound and developing means which comprise a coupling component and a neutral reacting salt of a weak base with a weak acid selected from the group consisting of the acetates and formates of lead, zinc, and cadmium, the material being free from dust.

2. A light-sensitive material which comprises a diazo compound and developing means which comprise a coupling component and zinc formate, the material being free from dust.

3. A light-sensitive material which comprises a rapidly coupling diazo compound and developing means which comprise a coupling component and a neutral reacting salt of a weak base with a weak acid selected from the group consisting of the acetates and formates of lead, zinc, and cadmium, the material being free from dust.

4. A light-sensitive material which comprises a diazo compound and developing means which comprise a coupling component and zinc acetate, the material being free from dust. v

. MAXIMILIAN PAUL SCHMIDT.

OSKAR siis. 

